Systems and methods for integrated microgrid management system in electric power systems

ABSTRACT

An integrated microgrid management system includes hardware operating as a node on an electrical power network. The node includes memory storing program code, a communications channel operatively connected to a plurality of controllable power devices, and a processor. In an embodiment, the processor is configured to implement a three-phase AC unbalanced model of a microgrid network, for both low and medium voltage networks. The processor is further configured to implement a topology processor that creates a map identifying controllable power devices that are connected to the network and how said controllable power devices are connected. The processor also implements an online power flow engine that uses the map and the three-phase AC unbalanced model of the network to generate commands to control the plurality of controllable power devices. Adaptive self-configuration logic and an optimization engine that performs multi-objective optimization are further disclosed.

This application is a continuation of U.S. patent application Ser. No.14/961,326 filed Dec. 7, 2015 (now U.S. Pat. No. 10,061,283), the entiredisclosure of which is incorporated herein by reference. Thisapplication includes material which is subject to copyright protection.The copyright owner has no objection to the facsimile reproduction byanyone of the patent disclosure, as it appears in the Patent andTrademark Office files or records, but otherwise reserves all copyrightrights whatsoever.

FIELD

The present invention relates in general to the field of electric powermanagement and automation systems (EPMAS), including DistributionManagement Systems (DMS), Energy Management Systems (EMS), NetworkManagement Systems (NMS) and Distributed Energy Resource ManagementSystems (DERMS). This application also relates to the subject matter ofU.S. patent application Ser. No. 14/480,038 filed Sep. 8, 2014, and U.S.patent application Ser. No. 14/612,013 filed Feb. 2, 2015, the entiredisclosures of which are incorporated herein by reference.

BACKGROUND

The introduction and integration of distributed energy resources (DER)into the electric power system (EPS, or “grid”) has become a priority inthe modern energy era. Distributed energy resources include resourcesthat provide generation (such as photovoltaic, fuel cell, wind, diesel,and natural gas generators), load (such as buildings, homes, andelectric vehicles), or storage (such as batteries, flywheels,supercapacitors, and pumped hydroelectric). In particular, theintegration of renewable energy sources and electric vehicles onto thegrid has many important economic and environmental benefits. Storage isconsidered as a “missing piece” of the distribution system, performingfunctions such as peak shaving/valley filling, Volt/VAR optimization,capacity relief, power quality management, buffering the intermittencyand variability of supply (e.g. power generation from renewable sources)and demand (e.g. electric vehicle charging or large thermostatic loads),providing backup power, and participating in power system ancillaryservices.

A microgrid can be defined as a group of interconnected loads anddistributed energy resources with clearly defined electrical boundariesthat acts as a single controllable entity with respect to the grid andcan connect and disconnect from the grid to enable it to operate in bothgrid-connected or island mode, according to the United States Departmentof Energy.

Today's microgrid controllers do not generally take into account theoverall configuration and operation of the power grid. Their primarypurpose is to optimize the operation within the microgrid itself under afixed electrical boundary without consideration for the external grid.The only consideration of the existing microgrid controllers is not toexceed some fixed limits for current, voltage, and frequency. Some ofmicrogrid controllers are able to accommodate work scheduling, on/offdevice switching, and outage management. Energy management is usuallybased on selective activation of a multiplicity of power generationequipment over a predetermined distribution and/or storage to supply amicrogrid of electrical power, and automatic, selective disconnect anyof power generators from providing power supply to the microgrid. Thedemand side is managed through conservation and demand response programsand premise (e.g. building, home) management and automation systems.Both of these approaches have little or no significance for distributionsystem operations. Microgrid controllers typically do not interoperatewith the distribution system's DMS, and little value can be attained forthe local distribution companies.

Various microgrid controller solutions have been provided in the priorart. The microgrid control system described in US Patent Application No.20140252855 to Tohru Watanabe, et al. is capable of controlling multiplefacilities according to characteristics of the facilities in order toachieve economic efficiency, environmental friendliness, and continuedoperability. The microgrid control system for controlling the operationsof the multiple power facilities is provided with a power supplyactivation/suspension planning unit that has a prediction unit forpredicting outputs or loads of power supply facilities or loadfacilities and a prediction unit for predicting prediction errorscontained therein. It is also provided with an economical loadallocation unit that determines command values related to thedistribution of loads to be borne by currently running power supplyfacilities.

In U.S. Patent Application No. 20140297051 to Huaguang Zhang, et al., anenergy resource-grid-load automatic control system is presented. Theenergy resource-grid-load automatic control system comprises adistributed renewable energy power generation module, a distributedrenewable energy inverter module, a conventional power generationmodule, a user load module, a bidirectional grid-connected controlmodule, a distributed renewable energy intelligent optimizing powergeneration control module, an energy storage module, an intelligentenergy storage unit adjuster and a storage battery pack. According tothe authors, this controller guarantees the stability and the highenergy utilization of the power generation system and effectively solvesthe problem of non-uniform frequency of use of storage batteries tounify the service life of the storage battery pack.

U.S. Patent Application No. 20130041516 to Uwe Rockenfeller, et al.presents a micro-grid controller that may control the generation,distribution, storage and use of electrical power on a micro-grid.Embodiments of a microgrid controller may include inputs for differenttypes of power (e.g. AC and DC) or power sources (e.g. wind and solar),an input for utility grid power, electrical equipment for conditioningthe electrical power received from the multiple sources (e.g. rectifiersand inverters), outputs to multiple types of loads (e.g. three-phase ACand single-phase AC) and control circuitry designed to control thegeneration, storage, distribution and usage of electrical power on themicrogrid. Embodiments of microgrid systems may include multiple typesof electrical generation sources (e.g. wind, solar, electromechanicaland fuel cell), multiple types of electrical loads (e.g. inductive andresistive), electrical storage units (e.g. batteries) and a microgridcontroller.

In U.S. Patent Application No. 20140300182 to John L. Creed, et al.,methods and control apparatus are presented for controlling supply ofelectrical power to a micro-grid power system, in which a mastercontroller automatically rebalances the micro-grid by activating anddeactivating individual power supplies to preferentially activatenon-fuel consuming power supplies and deactivate fuel consuming powersupplies so as to minimize fuel consumption for the micro-grid powersystem.

In U.S. Pat. No. 8,682,495 to Michael A. Carralero, et al., a method,apparatus, and computer program product is provided for configuring amicrogrid. A first configuration of the microgrid having a set ofmicrogrid elements is initialized. An address for each element in theset of microgrid elements of the microgrid is verified. In response toreceiving status data from the set of microgrid elements connected in apeer-to-peer network indicating a reconfiguration of the microgrid, theset of microgrid elements is re-aligned to form a second gridconfiguration. A second configuration of the microgrid is then executed.

In International PCT Patent Application No. WO2013015773 to HussamAlatrash, et al., a method, hierarchy, and control architecture forsupervisory control of microgrids and their respective energy resourcesmay be provided with the aim of building safe, reliable, and scalablemicrogrids. Furthermore, the hierarchy and control architecture may beaimed at supporting a host electrical power system stability and whilewaiving interconnection requirements that challenge system stability.

Although they provide specific microgrid functions, the above-referencedsolutions fail to address the issue of the overall power gridoptimization. They are generally not designed to contribute reactivepower to the grid in order to minimize losses or to improve voltageprofile along the distribution feeder. They do not adequately addressthe issue of significant power swings due to large loads (one-, two- orthree-phase) being randomly connected to the micro-grid.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, features, and advantages of theinvention will be apparent from the following more particulardescription of preferred embodiments as illustrated in the accompanyingdrawings, in which reference characters refer to the same partsthroughout the various views. The drawings are not necessarily to scale,emphasis instead being placed upon illustrating principles of theinvention.

FIG. 1 is a schematic diagram illustrating an embodiment of themicrogrid configuration.

FIG. 2 is a schematic diagram illustrating typical tiers of microgridsystems.

FIG. 3 is a schematic diagram illustrating a base case ofreconfiguration concepts of micro-grid systems.

FIG. 4 is a schematic diagram illustrating a second case ofreconfiguration concepts of micro-grid systems.

FIG. 5 is a schematic diagram illustrating a third case ofreconfiguration concepts of micro-grid systems.

FIG. 6 is a schematic diagram illustrating basic schematic of microgridsystems with a secondary network.

FIG. 7 is a state diagram illustrating an IMMS controller process flow.

DETAILED DESCRIPTION

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. The following description and drawings are illustrative andare not to be construed as limiting. Numerous specific details aredescribed to provide a thorough understanding. However, in certaininstances, well-known or conventional details are not described in orderto avoid obscuring the description. References to one or an embodimentin the present disclosure are not necessarily references to the sameembodiment; and, such references mean at least one.

Reference in this specification to “an embodiment” or “the embodiment”means that a particular feature, structure, or characteristic describedin connection with the embodiment is included in at least an embodimentof the disclosure. The appearances of the phrase “in an embodiment” invarious places in the specification are not necessarily all referring tothe same embodiment, nor are separate or alternative embodimentsmutually exclusive of other embodiments. Moreover, various features aredescribed which may be exhibited by some embodiments and not by others.Similarly, various requirements are described which may be requirementsfor some embodiments but not other embodiments.

The present invention is described below with reference to blockdiagrams and operational illustrations of methods and devices forvolt/VAR control in electric power management and automation systems. Itis understood that each block of the block diagrams or operationalillustrations, and combinations of blocks in the block diagrams oroperational illustrations, may be implemented by means of analog ordigital hardware and computer program instructions. These computerprogram instructions may be stored on computer-readable media andprovided to a processor of a general purpose computer, special purposecomputer, ASIC, or other programmable data processing apparatus, suchthat the instructions, which execute via the processor of the computeror other programmable data processing apparatus, implements thefunctions/acts specified in the block diagrams or operational block orblocks. In some alternate implementations, the functions/acts noted inthe blocks may occur out of the order noted in the operationalillustrations. For example, two blocks shown in succession may in factbe executed substantially concurrently or the blocks may sometimes beexecuted in the reverse order, depending upon the functionality/actsinvolved.

In an embodiment, the invention includes an Integrated MicrogridManagement System (IMMS) that provides a control system and frameworkdesigned for energy and cost optimization of one or more microgrids, andensures reliability and resiliency against power outages, while ensuringthat the equipment and other restrictions are observed at all times. Byproviding these functions, the IMMS facilitates the integration of loadswith significant power pulses, similar to Electric Vehicle (EV) chargingstations and all kinds of DERs. The IMMS is particularly valuable whenintegration of non-dispatchable DERs (PV or Wind) is required. Theoptimal use of such resources is challenging due to sudden swings ofavailable power that are not easy to predict and can have detrimentaleffect on frequency and voltage regulation if not treated properly. Inan embodiment, the IMMS uses dispatchable DERs, including theinverter-interfaced storage DERs and dispatchable loads (loads that canbe controlled under command that can be equivalent to a source), and anoptimized control strategy to mitigate problems introduced by suddenswings of real and reactive power. The IMMS can operate in a stand-alonemode or as a component of an EPS SCADA system, Distributed EnergyManagement System (DEMS), Distributed Energy Resource Management System(DERMS), Electricity Market or the like. When it operates within a DEMSor DERMS, the IMMS can provide the functionality of an Intelligent Node(IN). When it operates as a stand-alone device, the IMMS and the deviceit is implemented on can control either a grid-connected or a standalonemicro-grid.

The IMMS described below is preferably designed so that the microgrid isnot only locally optimized but can contribute to the overall power gridoptimization. In an embodiment, the IMMS can allow sharing of computingresources between controllers within a DEMS or DERMS and is meant to bea component in a distributed intelligence (DI) for managing the EPS.

Below, we first describe a complete microgrid configuration. On thisconfiguration basis, five typical tiers of microgrids are thendescribed: sub-premise, premise, community/sub-feeder, feeder andsubstation. And then, the real time reconfiguration of microgrid systemsis explained. The secondary network is introduced in the microgridsystems. Finally, the Integrated Microgrid Management System (IMMS) isdescribed.

FIG. 1 shows a schematic diagram illustrating the general layout of amicrogrid that the present IMMS is designed to control. The microgridmay consist of a number of DERs, three-phase EV fast chargers,bidirectional EV chargers, conventional three-phase loads and a host ofsingle- and two-phase loads connected to the microgrid via Smart ControlPanel. The microgrid may have one or more storage system DER units, andany number of Solar, Wind, Fuel Cell, AC variable speed and AC gridfrequency DERs. Special kinds of DERs are dispatchable loads.

In an embodiment, the IMMS controller presented in this document canmaintain real and reactive power balance within the microgrid forvoltage and frequency stability by managing dispatchable andnon-dispatchable generation, storage, and load resources. The IMMS canalso manage constraints such as resource availability, ramp rates, andcurrent limits. The IMMS can manage grid-connected and grid-islandedstates to connect or disconnect the microgrid from the main grid basedon factors including price points and availability of the main grid.Within a certain mode the IMMS can optimize the operation of themicrogrid such as according to cost, environmental, reliability orconvenience objectives.

The microgrid shown in FIG. 1 may be connected to the EPS via a currentconstrained tie. The IMMS controller can provide a microgrid withcapability to handle significant random high-power loads (e.g. multipleEV chargers or large compressors), without exceeding constraints usingmicrogrid DERs. At the same time, the IMMS can accommodate random poweroutput from renewable DERs and enables DEMS (or DERMS) to utilizereactive power capacity of all interface inverters to assist in optimaloperation of EPS. To enable microgrid optimization, single- andtwo-phase loads can be connected via a smart panel that enablesswitching loads between phases. Based on an IMMS command, a smart panelcan provide phase balancing as well as load shedding and load cycling(e.g., to ensure optimal charging of multiple EVs that are connectedvial level 2 chargers). The IMMS enables easy integration of gridcomponents such as DER controllers, sensors, metering collectors, switchcontrollers, and substation intelligent electronic devices (IED) toprovide full intelligent node (IN) functionality.

By default, all inverters follow the voltage and frequency specified bythe grid. Based on measurements and results of the power flow, the IMMSdetermines optimal operating points for each source and sends individualset-points to all units. When all loads cannot be accommodated withavailable power, intelligent load shedding is implemented. If needed,the IMMS has the ability to activate a Frequency vs. Active Power andVoltage vs. Reactive Power droop control mode. This is particularlyimportant if the power produced in the microgrid represent a significantcontribution to the overall power produced in EPS. In such case themicrogrid has the ability to operate as a Virtual Power Plant (VPP) andutilities may impose specific rules for connection.

The IMMS accommodates advanced EV charging by utilizing local DERs andrelies on battery storage to provide pre-specified power ramp rate andensures that grid tie maximum power is not exceeded. Since most of EVcharging is controlled by electric vehicles it may result in significantload power pulses. IMMS ensures that these pulses are maintained withinthe predefined range. If bidirectional EV chargers are installed, whichcan inject power from the vehicle's battery back into the grid, the IMMScan utilize the available EV batteries to improve the operation of thegrid.

The IMMS provides support for global volt VAR optimization (VVO). Eachone of converter-based DERs can provide reactive power on request aslong as the maximum tie-line current is not exceeded.

In an embodiment, operations for the DEMS or DERMS are carried out on atleast one Intelligent Node (IN) which acts as the brains of the grid andruns the IMMS software. Each IN consists of a hardware and softwareplatform, with data/information processing (e.g. intelligence, decisionmaking) and communications (e.g. networking, protocol conversion, localand wide area) capabilities. A micro-grid controlled by the IN can bedesigned to operate in a grid-connected mode with occasional islandedoperation.

In an embodiment, the IMMS-controlled microgrid operates in one of thefollowing modes: Grid-supported mode, VPP mode, or Islanded mode.

In Grid-supported mode, the microgrid operates as a four-quadrant(positive and negative voltage and current) device with imposed currentlimit at the point of connection. It is expected that the balance ofpower is provided by the grid.

In VPP mode, the microgrid is able to control voltage at the point ofconnection. It can inject required active and reactive power, as well asP and Q droop based on frequency and voltage.

In Islanded mode, the IMMS controller is capable of providing stablevoltage and frequency while dynamically balancing available generation,storage and loads. Load shedding based on predetermined criteria isavailable. Supply of critical loads can be maintained for extendedperiods of time.

In an embodiment, the IMMS controller described herein is capable ofdynamic transfer between modes of operation. It is able to recognize ablackout signature and initiate islanded mode before the supply tocritical loads is interrupted. The IMMS can also support adaptiveself-configuration. A micro-grid typically contains a number of DGs,loads and other microgrids. As a response to grid events, one set ofmicrogrids can be reconfigured into various microgrids, includingembedded microgrids.

With continued reference to FIG. 1, the network in the middle of thefigure represents the main power circuit of the microgrid. Throughbreakers, the network nodes are connected to different distributedenergy sources and loads. Each breaker in the microgrid is associatedwith an Intelligent Node.

On the left hand side of the Network are the distributed energy sources.It includes Tidal, Storage system, Solar, Fuel cell, Wind, AC Gen.Variable frequency, and AC Generator grid frequency. In all types of thedistributed energy sources, AC Generator grid frequency only is directlyconnected to the Network. Other sources have its own interface to beconnected to the network because its frequency is variable.

On the right hand side of the Network are the loads and single and twophases distributed energy sources. A smart control panel is set tocontrol and manage the unbalanced loads and single and two phasesdistributed energy sources.

The top, Power Interface Ports, represents all the connections to theelectrical power system.

The second from bottom, Microgrid Controller (consisting of one or moreintelligent nodes, all running IMMS), is the controller of themicrogrid. It is in charge of the control and power management of themicro-grid.

The bottom, EPS SCADA, DEMS, DERMS, Electricity Market or similar, isthe utility's control center. The Microgrid Controller will receivecommands and related information.

Power Interface Ports 101 represents the electrical power system andthrough a breaker 105 (intelligent node) connect to the microgridNetwork 110, which may include one or more points of connection. Network110 is the main power circuit of the microgrid. Tidal power source 102through Tidal Interface 103 and the breaker 104 is connected to theNetwork. Storage System 115 through Storage Interface 116 and thebreaker 111 is connected to the Network. Solar power source 119 throughSolar Interface 120 and the breaker 117 is connected to the Network.Fuel Cell source 125 through Fuel Cell Interface 126 and the breaker 123is connected to the Network. Wind power source 130 through Wind powerInterface 131 and the breaker 128 is connected to the Network. AC Gen.Variable frequency source 135 through AC Gen. Variable frequencyInterface 136 and the breaker 133 is connected to the Network. ACGenerator grid frequency source 140 through the breaker 138 is connectedto the Network.

Smart Control Panel 112 is connected through the breaker 112 to theNetwork, through one-phase load interface 107 is connected to one-phaseloads 109, through two-phase load interface 108 is connected totwo-phase loads 113, through one-phase DER interface 122 is connected toone-phase DER 114, and through two-phase DER interface 121 is connectedto two-phase DER 118.

Bidirectional EV Chargers 127 is connected through the breaker 124 tothe Network. Three-phase EV Fast Chargers 132 are connected through thebreaker 129 to the Network. Dispatchable Loads 137 are connected throughthe breaker 134 to the Network. Common three-phase Loads 141 areconnected through the breaker 139 to the Network.

In an embodiment, Microgrid Controller (142) consists of one or moreintelligent nodes and is responsible for the control and powermanagement of the microgrid. Every controllable power device andintelligent node in the microgrid communicates and exchanges informationwith the Microgrid Controller 142.

EPS SCADA, DEMS, DERMS, Electricity Market or similar controller 143 isthe utility's control central. It communicates with the MicrogridController 142 and exchanges information.

The five typical tiers of microgrid systems are shown in FIG. 2. Thisfigure illustrates the scalable multi-tiered architecture of microgridsystems. Each breaker in a microgrid is an Intelligent Node.

The descriptions of components are as follows:

-   -   a. Tier 1: Dotted line 210 represents a sub-customer microgrid,        defined as one or more circuits inside a customer premise behind        a utility meter. In this instance, the sub-customer micro-grid        is connected to the main grid through breaker 215 controlled via        an intelligent node running IMMS.    -   b. Tier 2: Dotted line 208 represents a customer, defined as the        complete set of circuits behind a utility meter. In this        instance the customer microgrid is connected to the main grid        through a breaker 213. 208 further has an embedded microgrid        210. Through the breakers 212, 214, and 215, the microgrid 208        can be reconfigured.    -   c. Tier 3: Dotted line 207 represents a type of sub-feeder or        community microgrid, defined as consisting of a number of        utility customers but not the entire feeder. In this instance        the microgrid is connected through two breakers 211 and 214 to        the main grid. Through the breakers 211 and 213, the microgrid        207 can be reconfigured. The other feature of micro-grid 207 and        microgrid 208 is with a common part of the system. It shows the        microgrid has an overlapping feature.    -   d. Dotted line 206 represents another type of sub-feeder or        community microgrids. In this instance the microgrid is        connected through a breaker 209 to the main grid. In micro-grid        206, the microgrid 207, 208, and 210 are embedded. And also,        microgrid 206 can be reconfigured through breakers 211, 212,        213, 214, and 215.    -   e. Tier 4: Dotted line 205 represents a type of feeder based        microgrid, defined as consisting of all customers possibly fed        by a single utility distribution feeder. In this instance the        micro-grid is connected through a breaker 204 to the main grid.        Similar to microgrid 206, micro-grid 205 also has embedded        microgrids and can be reconfigured through internal breakers.    -   f. Tier 5: Dotted line 203 represents a type of substation based        microgrid, defined as consisting of all customers possibly fed        by a single utility distribution substation. In this instance        the microgrid is connected through a breaker 202 to the main        grid. Similar to micro-grid 205, microgrid 203 also has embedded        microgrids and can be reconfigured through internal breakers.

Electrical Power System (EPS) 201 feeds the substation through thebreaker 202.

FIG. 3 shows a base case of real time reconfiguration of microgridsystems. Then, on this basis, FIGS. 4 and 5 (discussed further below)show details of the microgrid reconfiguration concept. In FIG. 3, EPS301 feeds the substation through the breaker 302. Breakers 303 and 306are breakers in the sample feeder that can be used to section thefeeder. Dotted line 304 represents a microgrid in the feeder and througha breaker 307 is connected to the grid. Dotted line 305 represents thesecond microgrid in the feeder and through a breaker 308 is connected tothe grid. Microgrid 305 can be reconfigured through the breaker 309.

FIG. 4 illustrates further the real-time reconfiguration conceptspresented above. EPS 401 feeds the substation through the breaker 402.Breakers 403 and 406 are breakers in the sample feeder to be used tosection the feeder. Dotted line 404 represents a microgrid in the feederand through breakers 406 and 408 are connected to the grid. 404 is fromreconfiguration of microgrid 304 in FIG. 3. Dotted line 405 representsthe second microgrid in the feeder and through a breaker 309 isconnected to the grid. 405 is from reconfiguration of microgrid 305 inFIG. 3.

FIG. 5 further illustrates the above-described real-time reconfigurationconcepts of micro-grid systems. EPS 501 feeds the substation through thebreaker 502. Feeder breaker 503 is a breaker in the sample feeder andcan be used to connect the feeder to the substation. Dotted line 504represents the microgrid in the feeder and through breaker 505 isconnected to the grid. 504 is from the reconfiguration of microgrid 404and 405 in FIG. 4. 504 can be reconfigured through breakers 506, 507,and 508.

The microgrid can be maintained in a variety of feeder configurations,such as radial, dual radial, open loop, closed loop (mesh), andsecondary networks. A basic schematic of microgrid systems with asecondary network is shown in FIG. 6. The secondary network areconnected to two feeders through breakers 611 and 614. In the secondarynetwork, there are two independent microgrids. Dot line 609 is connectedto the secondary network through breaker 612 and the other is connectedto the secondary network through breaker 613. Based on the systemconditions, the secondary network can be included in the microgrid 605(right hand side feeder) or the left hand side micro-grid.

With continued reference to FIG. 6, EPS 601 represents the ElectricalPower System and through the breaker 603 feeds the substation. Dottedline 605 represents the microgrid of the feeder at the right hand sidewhich is connected to substation through breaker 604. This microgrid canbe reconfigured through breakers 607, 610 614, 613, 612, and 611. Dottedline on the left hand side feeder represents the other microgrid whichis connected to substation through breaker 602. This microgrid can bereconfigured through breakers 608, 611 612, 613, and 614.

A method of controlling microgrids is described in the state machinepresented in FIG. 7. Reference no. 701 represents the command to startthe micro-grid controller and the micro-grid. Reference no. 702represents the initialization process of the micro-grid controller.Dotted line 703 on the left hand side represents the internal control ofthe micro-grid controller. Reference no. 704 represents that themicro-grid is at off status. Reference no. 705 represents the transitionto the micro-grid off status. Reference no. 706 represents the processchecking the availability of the grid. Reference no. 707 represents thetransition to the grid connected mode or to off status. Reference no.708 represents the process checking the DG power to run the micro-gridat islanded mode. Reference no. 709 represents the micro-grid running atgrid connected mode. Reference no. 710 represents the external faultdetection function. Reference no. 711 represents the regular processchecking the DG power for the islanded mode. Reference no. 712represents the transition to the Islanded mode. Reference no. 713represents the process checking the DG power to run an islanded mode.Reference no. 714 represents the micro-grid running in islanded mode.Reference no. 715 represents the process ending the islanded mode.Reference no. 716 represents the outputs from internal controller.Reference no. 717 represents the internal fault detection function.Reference no. 718 represents that the microgrid is at internal fault.Reference no. 719 represents the manual operator. Reference no. 720represents the commands from manual operator to the internal controller.

The above-described Integrated Microgrid Management System (IMMS)provides a novel and advantageous approach in a number of ways, some ofwhich are described below.

Microgrid Platform Services

The IMMS can be architected as a “core” set of functions composed of:

-   -   a. a library of engineering models of energy resources,        including generation, storage, and demand resources, such as        solar, wind, diesel, battery, flywheel, fuel cell, hydro and        electric vehicles;    -   b. a three-phase AC unbalanced engineering model of the        microgrid network, including low voltage and medium voltage        networks, such as underground cables, overhead wires,        transformers, switches, fuses, reclosers, voltage regulators,        capacitors, elbows and terminators;    -   c. a topology processor of what resources are connected to the        network and how they are connected;    -   d. a forecasting engine for generation (supply), storage and        loads (demand);    -   e. an online power flow engine, using the three-phase AC        unbalanced model of the network, for both low and medium voltage        networks;    -   f. a state estimator, to compute system states such as voltages,        currents, power, frequency, and angles, for the online power        flow engine;    -   g. an optimization engine, running optimization algorithms such        as non-linear programming (NLP), for multi-objective,        multi-constraint, and multi-agent optimization, where the        concept of Pareto fronts is used for multi-objective        optimization and the concept of Correlated equilibrium        (including Nash equilibrium as a specific case) is used for        multi-agent optimization.

The IMMS can be configured by defining a number of available energyresources from the library and their point of connection onto themicrogrid network engineering model, to build up the model. There is nolimitation to the number of available energy resources, and that theIMMS can be expanded and scaled in both energy resources and microgridnetwork.

In an embodiment, on top of the above-described core is a library ofapplications for various modes of operation, which include Grid-islandedmode and Grid-connected mode. In Grid-islanded mode, the microgrid isself-sufficient with by managing embedded dispatchable andnon-dispatchable generation, storage, and load resources, which canmaintain real and reactive power balance within the microgrid forvoltage and frequency stability. In Grid-connected mode, the microgridis connected to the larger electric power system, and is reliant on itto maintain real and reactive power balance within the microgrid forvoltage and frequency stability. In this mode the microgrid can balanceits supply, demand and storage resources to meet optimization objectivesincluding cost, environmental impact, reliability and convenience. TheIMMS can manage the transition between these two modes.

Intelligent Node Network Driven

In accordance with an embodiment, a method is provided for controllingthe microgrid through an Integrated Microgrid Management System (IMMS)embedded into one or more controllers as Intelligent Nodes. Suchintelligent nodes can be physical and local to the microgrid, orvirtualized as software controls outside the physical premise of themicrogrid, such as a remote supervisory management system.

Multiple microgrids, whether they are at different tiers or overlapping,can be coordinated via a network of IMMS controllers, connected via acommunications system.

Integrated Multi-Tiered Optimization

The operation of the microgrid, including balancing its supply, storageand demand resources to meet various objectives, does not only take intoconsideration its own internal objectives within a fixed electricalboundary, but how it interfaces with upstream, downstream, adjacent oroverlapping systems, including other microgrids.

Five typical tiers of microgrids include sub-premise, premise,community/sub-feeder, distribution feeder, and substation tiers. Premisecan include residential, commercial and industrial customers.

A microgrid is hence a “grid-of-grids”, such that that IMMS can be runwith multiple instances at different tiers, and be able to interoperate.

Adaptive Self-Configuration

In an embodiment, the boundaries of the microgrid are not fixed. Undercertain criteria such as defined by thresholds, events such as faults,or optimization parameters, the microgrid can be reconfigured intovarious configurations. Forms of reconfiguration include formulatingdifferent tiers, embedded, and overlapping microgrids.

Control of microgrid boundaries can be dynamic, and can adjust/adapt tovarious grid and micro-grid operating conditions. Microgridconfiguration can operate over various distribution network topologies,including radial, dual radial, open loop, closed loop (mesh), andsecondary networks.

Aggregation

The operation of multiple microgrids can be coordinated via theabove-described intelligent node network, and their energy resourcecapacities aggregated and controlled by a highest-tier IMMS which embedsall the IMMS's in consideration.

Such coordinated operations and aggregated capabilities are commonlyreferred as a Virtual Power Plant (VPP) or the Energy Cloud.

Hardware

At least some aspects disclosed above can be embodied, at least in part,in software. That is, the techniques may be carried out in a specialpurpose or general purpose computer system or other data processingsystem in response to its processor, such as a microprocessor, executingsequences of instructions contained in a memory, such as ROM, volatileRAM, non-volatile memory, cache or a remote storage device.

Routines executed to implement the embodiments may be implemented aspart of an operating system, firmware, ROM, middleware, service deliveryplatform, SDK (Software Development Kit) component, web services, orother specific application, component, program, object, module orsequence of instructions referred to as “computer programs.” Invocationinterfaces to these routines can be exposed to a software developmentcommunity as an API (Application Programming Interface). The computerprograms typically comprise one or more instructions set at varioustimes in various memory and storage devices in a computer, and that,when read and executed by one or more processors in a computer, causethe computer to perform operations necessary to execute elementsinvolving the various aspects.

A non-transient machine-readable medium can be used to store softwareand data which when executed by a data processing system causes thesystem to perform various methods. The executable software and data maybe stored in various places including for example ROM, volatile RAM,non-volatile memory and/or cache. Portions of this software and/or datamay be stored in any one of these storage devices. Further, the data andinstructions can be obtained from centralized servers or peer-to-peernetworks. Different portions of the data and instructions can beobtained from different centralized servers and/or peer-to-peer networksat different times and in different communication sessions or in a samecommunication session. The data and instructions can be obtained inentirety prior to the execution of the applications. Alternatively,portions of the data and instructions can be obtained dynamically, justin time, when needed for execution. Thus, it is not required that thedata and instructions be on a machine-readable medium in entirety at aparticular instance of time.

Examples of computer-readable media include but are not limited torecordable and non-recordable type media such as volatile andnon-volatile memory devices, read only memory (ROM), random accessmemory (RAM), flash memory devices, floppy and other removable disks,magnetic disk storage media, optical storage media (e.g., Compact DiskRead-Only Memory (CD ROMS), Digital Versatile Disks (DVDs), etc.), amongothers.

In general, a machine readable medium includes any mechanism thatprovides (e.g., stores) information in a form accessible by a machine(e.g., a computer, network device, personal digital assistant,manufacturing tool, any device with a set of one or more processors,etc.).

In various embodiments, hardwired circuitry may be used in combinationwith software instructions to implement the techniques described above.Thus, the techniques are neither limited to any specific combination ofhardware circuitry and software nor to any particular source for theinstructions executed by the data processing system.

The above embodiments and preferences are illustrative of the presentinvention. It is neither necessary, nor intended for this patent tooutline or define every possible combination or embodiment. The inventorhas disclosed sufficient information to permit one skilled in the art topractice at least one embodiment of the invention. The above descriptionand drawings are merely illustrative of the present invention and thatchanges in components, structure and procedure are possible withoutdeparting from the scope of the present invention as defined in thefollowing claims. For example, elements and/or steps described aboveand/or in the following claims in a particular order may be practiced ina different order without departing from the invention. Thus, while theinvention has been particularly shown and described with reference toembodiments thereof, it will be understood by those skilled in the artthat various changes in form and details may be made therein withoutdeparting from the spirit and scope of the invention.

What is claimed is:
 1. An integrated microgrid management system,comprising: hardware operating as a node on an electrical power network,the node comprising: memory storing program code; a communicationschannel operatively connected to a plurality of controllable powerdevices; a physical processor configured to: implement a three-phase ACunbalanced model of a microgrid network, for at least one of: low andmedium voltage networks; implement a topology processor that creates amap identifying controllable power devices that are connected to thenetwork and how said controllable power devices are connected; and,implement an online power flow engine that uses the map and thethree-phase AC unbalanced model of the network to generate commands tocontrol the plurality of controllable power devices.
 2. The integratedmicrogrid management system according to claim 1, wherein thecommunications channel is further operatively connected to one or moreother integrated microgrid management systems.
 3. The integratedmicrogrid management system according to claim 1, wherein the processoris further configured to utilize a library of engineering models ofenergy resources.
 4. The integrated microgrid management systemaccording to claim 3, wherein the energy resources comprise at least oneof: generation resources, storage resources, or demand resources.
 5. Theintegrated microgrid management system according to claim 4, wherein thegeneration resources comprise at least one selected from the setconsisting of: tidal, solar, hydroelectric, fuel cell, wind, and A/Cgenerator.
 6. The integrated microgrid management system according toclaim 1, wherein the processor is further configured to implement astate estimator that computes system states.
 7. The integrated microgridmanagement system according to claim 6, wherein the system statescomprise at least one state selected from the set consisting of:voltages, currents, power, frequency and angles.
 8. The integratedmicrogrid management system according to claim 1, wherein the processoris further configured to use dispatchable distributed energy resourcesand an optimized control strategy to mitigate problems introduced byswings of real and reactive power.
 9. The integrated microgridmanagement system according to claim 1, wherein the hardware operatingas a node on the electrical power network comprises an electrical powerSCADA system.
 10. The integrated microgrid management system accordingto claim 1, wherein the hardware operating as a node on the electricalpower network comprises a distributed energy management system.
 11. Theintegrated microgrid management system according to claim 1, wherein thehardware operating as a node on the electrical power network comprises adistributed energy resource management system.
 12. The integratedmicrogrid management system according to claim 1, wherein the microgridis a grid-connected microgrid or an islanded or standalone micro-grid.13. The integrated microgrid management system according to claim 1,wherein the processor is further configured to maintain real andreactive power balance within the microgrid for voltage and frequencystability by managing dispatchable and nondispatchable generation,storage, and load resources.
 14. The integrated microgrid managementsystem according to claim 1, wherein the processor is further configuredto utilize a library of applications corresponding to a plurality ofdifferent modes of microgrid operation.
 15. The integrated microgridmanagement system according to claim 14, wherein the plurality ofdifferent modes of microgrid operation comprise Grid-islanded mode andGrid-connected mode.
 16. The integrated microgrid management systemaccording to claim 1, wherein the processor is further configured tomanage grid-connected and grid-islanded states to connect or disconnectthe microgrid from a main grid based on factors including price pointsand availability of the main grid.
 17. An integrated microgridmanagement system, comprising: hardware operating as a node on anelectrical power network, the node comprising: memory storing programcode; a communications channel operatively connected to a plurality ofcontrollable power devices; a physical processor configured to:implement an optimization engine that is configured so as to performlocal microgrid optimization and to contribute to optimization of anoverall power grid; and, implement a power flow engine that uses outputof the optimization engine to generate commands to control the pluralityof controllable power devices.
 18. An integrated microgrid managementsystem, comprising: hardware operating as a node on an electrical powernetwork, the node comprising: memory storing program code; acommunications channel operatively connected to a plurality ofcontrollable power devices; a physical processor configured to:implement adaptive configuration logic that: determines a firstoperating configuration of boundaries of a micro-grid; determines thatpredetermined criteria have been met and, based on said determination,determines a reconfiguration of boundaries of the microgrid, thereconfiguration being a second operating configuration that differs fromthe first operating configuration; generates commands to control theplurality of controllable power devices so as to reconfigure boundariesof the microgrid in accordance with the second operating configuration.19. The integrated microgrid management system according to claim 18,wherein the first operating configuration comprises a first tier typeand the second operating configuration comprises a second tier type, thesecond tier type being different than the first tier type.
 20. Theintegrated microgrid management system according to claim 18, whereinthe criteria comprises a threshold or an event.